The introductory blog post has a lot more information

https://microsoft.ai/news/introducingmai-code-1-flash/

and the model card

https://microsoft.ai/pdf/MAI-Code-1-Flash-Model-Card.PDF

The broader announcement of 7 MAI models seems to be where the 5B active in the title comes from

https://microsoft.ai/news/building-a-hillclimbing-machine-la...